1. Field of the Invention
This invention relates to display systems and particularly to an improved histogram equalization system operable in response to video signals to develop truncated video signals having the property of providing an image with enhanced details.
2. Background of the Invention
Histogram equalization is a unique image contrast enhancement technique and historically has been applied to an entire picture frame in nonreal time computer software mechanizations. In histogram equalization the intensity coding of the video is redistributed by the regeneration of a digital video truncation matrix which when utilized to control the digitized video results in an equal number of elements at each display intensity level. In real time systems such as radar systems, laser systems, and infrared systems, truncation of the input video is conventionally performed either by linear truncation which involves utilizing a selected number of most significant bits or by logarithmic truncation generally utilizing logarithmic values stored in a read only memory. These types of trunction systems provide some contrast enhancement in the display picture but have the disadvantage of not being adaptable variations of the intensity level of the scene. It would be a substantial advantage in the art to provide a histogram equalization system operable in real time in response to video data that with a simplified mechanization adapts itself to scene variations to improve the picture detail and contrast properties.